Nitric nitrogen is the necessary nutritive element for growth and metabolism in plants, and nitrogen is the component for many important organic compounds in plants, including proteins, chlorophylls, nucleic acids and a variety of bio-enzymes, therefore, both the lack and excessive application of nitric nitrogen will result in decrease of crop yield.
There are several methods for analyzing the nitric nitrogen in plants, such as a distillation process, a diffusion process and a nitrate boiling process for concentrated sulfuric acid and the like. Although the above-mentioned methods have high detection precision, they consume more time, have higher experimental cost, and have irreparable destructive effects for plants.
The ion microelectrode is capable of rapidly detecting the nutrition level of nitric nitrogen in crops. The content of nitric nitrogen can be analyzed by detecting the concentration of nitrate ions in plants. Chinese Patent No. 200510088935.0 discloses a nondestructive detection method and a portable measuring instrument for nitrogen element and moisture content in plants, which calculates the nutrition level of plants by detecting the light transmittance for fresh leaves, but has high instrument cost. Chinese Patent No. 201310164638.4 discloses a high-spectrum-based rapid nondestructive high-accuracy method for identifying the abundance degree of nitrogen element in a plant leaf, which also needs a relatively large system and cannot detect the nutrition level of the crops in real-time and on site. Sutter Company developed an ion microelectrode detection system in 2012, which is unfavorable for real-time in-vivo nondestructive detection of ion concentration in crops due to the relatively large system; furthermore, since the microelectrode is exposed to the outside, the taper end of the microelectrode is vulnerable and extremely unsafe, thus the detection cost is greatly increased.